1. Field of the Invention
The present invention relates to converters and, more particularly, to a converter which can be used as, for example, a flash-type A-D converter.
2. Description of the Related Arts
In order to change a threshold voltage Vt of a flash-type inverter utilizing a CMOS, a gate length (L) and a gate width (W) of a transistor therein have been changed (refer to, for example, "A-D Converters Principally Comprised of a CMOS Inverter", C-608, 1982 Spring Convention, Congress on Electronic Information Communication or unexamined Japanese patent publication (KOKAI) No. H5-203681).
Providing a multiplicity of transistors having different gate lengths and gate widths on a single substrate makes the layout design complicated. Further, in order to provide a multiplicity of transistors having different gate lengths and gate widths on the same substrate, the minimum design rules must be applied to the smallest transistor, which results in a problem that a surface area of the chip must be increased to provide transistors of larger sizes.